Investigation of the Mn binding site in cytochrome c oxidase from Paracoccus denitrificans by high-frequency EPR

Käss, Hanno, MacMillan, Fraser ORCID: https://orcid.org/0000-0002-2410-4790, Ludwig, Bernd and Prisner, Thomas F. (2000) Investigation of the Mn binding site in cytochrome c oxidase from Paracoccus denitrificans by high-frequency EPR. The Journal of Physical Chemistry B, 104 (22). pp. 5362-5371. ISSN 1089-5647

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Abstract

Cytochrome c oxidase contains a redox-inactive metal center of unknown function. It has been shown that for Paracocccus denitrificans, depending on growth conditions, Mn2+ ions can occupy the Mg2+ site in the functional protein. Differences between the 9.5 GHz X-band electron paramagnetic resonance (EPR) spectra of such Mn2+ preparations in oxidized and reduced state have previously been interpreted as being due to conformational changes. However, only minor differences have been found in analogous 34 GHz Q-band EPR experiments on Mn2+ containing cytochrome c oxidase from Rhodobacter sphaeroides. The new temperature-dependent X-, Q- and 95 GHz W-band EPR data from Paracoccus preparations shown here provide a consistent explanation of these contrasting former interpretations. The EPR spectra of oxidized samples reveal contributions of a dipolar interaction between the Mn2+ spin and the paramagnetic dinuclear Cu-A center. In reduced samples, the Cu-A center is diamagnetic, and thus, a pure Mn2+ signal is found. The zerofield parameters D and E are 145 +/- 10 (120 +/- 5) G and 28 +/- 5 (22 +/- 3) G in the fury oxidized (reduced) protein. From the evaluated dipolar coupling constant of 33.6 +/- 1 G, an averaged distance between Mn2+ and the Cu-A center of 9.4 +/- 0.2 Angstrom was calculated, providing an independent confirmation of the distance calculated from the 2.7 Angstrom X-ray structure.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Chemistry (former - to 2024)
UEA Research Groups:	Faculty of Science > Research Groups > Biophysical Chemistry (former - to 2017) Faculty of Science > Research Groups > Chemistry of Life Processes Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry Faculty of Science > Research Groups > Chemistry of Light and Energy
Depositing User:	Rachel Smith
Date Deposited:	19 Jul 2011 11:00
Last Modified:	24 Sep 2024 10:27
URI:	https://ueaeprints.uea.ac.uk/id/eprint/33883
DOI:	10.1021/jp993133j

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